EFI/MPI hard start after heat soaked

[DeeVee]

This may be coincidence and means nothing but next time if this happens to you, try to turn on bilge blower and see if it helps. Mine is 5.0MPI A1 Gen II with ВЅ-3/4 tank of gas. Don't know if it would works on Carb's engine.

Yesterday(7/6) was 91*f /98* heat index. Today(7/7) was 94*f with heat index up to 104*, little breeze once in a while. It happened to me on yesterday and while trying to keep engine running by open/pump the throttle(in neutral), seem like no gas get in(or choking) and engine is bogging down, I turn on the bilge blower and engine rpm picks up instantly, (yes I forgot turning on the blower before start engine) but anyway. I tried to reproduce the problem again today and yes it's happens again after I anchored for an hour or so, engine would start but then stalls again and the symptom is just the same as of yesterday, turning on the bilge blower would takes care of that again. So..my though is it's too hot and there's lack of air down in engine room, by turning on blower, more “fresh air" get down there and engine can breathe easier.

 

[Billylll]

It sure has been hot as all get out here on the Jersey coast as well. I don't have that problem but it sounds like your passive air flow might be limited. However this could be masking another issue with the fuel delivery system or a sensor that controls the IAC or injectors pulse width and duration?
I have had bigger problems keeping the boat cool in these temps.
Bill

 

[Rustydog]

With an automotive MPI you can cycle the key off and on several times to cycle the fuel pump. This puts fresh liquid fuel in the fuel rails.

 

[Sandy]

It's hard to take back an explosion if you neglect to run the blower before every start even if ...you meant to. Sounds like a good change in habit for the safer will also help hot starting. I've seen some very nasty effects( to POB's and boat) of gas boat explosions on other peoples' boats. That serves as an pretty effective reminder to me.

Rustydog's suggestion works the same on boats. You could also try moving throttle to full which turns off the injectors during starting , just to rule out the opposite issue, flooding.